It is known in the art to cure a blend of epoxy resin and blocked isocyanate prepolymer with an amine. For instance, in Mobay Product Information Bulletin "Desmocap 11A" such cures are described. In the Mobay literature, in an article titled "New Solvent-Free Epoxy/Polyurethane Combinations", Wellner, Gruber and Ruttman disclose information on properties exhibited for systems cured with Laromin C-260, isophorone diamine or trimethylhexamethylene diamine. Cycloaliphatic diamines were described as particularly successful.
A paper generated at the Kelso & Cibulas, SPI-ERF Meeting, Atlanta, Nov. 30, 1983 describes combinations of isocyanate prepolymers blocked with alkyl phenols and liquid epoxy resins which form stable mixtures. Such mixtures were quite reactive with amines. Amines cited were 3,3'-dimethyl-4,4'-diaminocyclohexylmethane (commercially available as Laromin C-260), bis(aminopropyl)piperazine, a polyglycol diamine and isophorone diamine. Properties given were those obtained with Laromin C-260.
In the related work in the art the products resulting from curing epoxy resin and blocked isocyanate prepolymer blends with amines are brittle materials with few redeeming characteristics. The amine curatives are often hindered amines.
It would be a distinct advantage in the art if a amine component could be used in a curing system which would allow for a product which was not brittle, but very tough and impact resistant and useful for producing flexible coatings, castings and sealants that cure rapidly at ambient temperatures. It would also be advantageous if the amines were effective using only small amounts of isocyanate prepolymer to yield products with desirable properties.